A geomorphological framework for river characterization and habitat assessment

1. Methods to assess the physical habitat available to aquatic organisms pr ovide important tools for many aspects of river management, including river health monitoring, determination of river restoration/rehabilitation strat egies, setting and evaluating environmental flows and as surrogates for bio diversity assessment. 2. Procedures used to assess physical habitat need to be ecologically and g eomorphologically meaningful, as well as practicable. A conceptual methodol ogical procedure is presented that evaluates and links instream habitat and geomorphology. 3. The heterogeneity of habitat potential is determined within geomorphic u nits (such as pools, runs, riffles) by assessing flow hydraulics and substr ate character. These two variables are integrated as hydraulic units - patc hes of uniform flow and substrate. 4. This methodology forms a logical extension of the River Styles framework that characterizes river form and behaviour at four inter-related scales: catchments, landscape units, River Styles (reaches) and geomorphic units. A s geomorphic units constitute the basis to assess aquatic habitat availabil ity, and they form the building blocks of river and floodplain systems, int act reaches of a particular River Style should have similar assemblages of instream and floodplain habitat. 5. An application of the hydraulic unit procedure is demonstrated in gorge, partly-confined and alluvial River Styles front the Manning catchment in n orthern New South Wales, Australia. Copyright (C) 2001 John Wiley & Sons, L td.